New Class - The Sage

I was reading an OSR blog somewhere that mentioned an adventuring sage class (I think from Dave Arneson). Here is my ACKs version. The expert knowledge mnight be a little over powered, but it does allow a sage to get some specific knowledge skills at a level in which they can actually be, you know, a sage. Please let me know what you think.

Sages are masters of knowledge, research and learning. Their thirst for knowledge sometimes leads them into danger, so they learn basic skills to survive.

Sages learn basic combat training. At first level, sages hit an unarmored foe (AC 0) with an attack throw of 10+. They advance in attack throws and saving throws by two points every four levels of experience. They cannot wear armor or use shields. They may use swords, daggers, bows, or crossbows. They may fight with a one handed weapon, or with a weapon in each hand.

A sage saves as a mage. They can use any magical item usable by mages, or any magical weapon they are proficient with. They gain proficiencies as a thief.

At 1st level a sage starts with one class proficiency, a general proficiency, and a Knowledge proficiency of their choice. (1 custom power). A sage’s specialized research and training allows them expert knowledge. As a result, any time they choose a new knowledge proficiency, profession – librarian or scribe, or the engineering proficiency, they automatically begin with two levels of that proficiency (2 custom powers).

Sages have a general level of loremastery (1 custom power). A sage can decipher occult runes, remember ancient history, identify historic artifacts, and similar tasks. At 1st level, the character must make a proficiency throw of 18+ on 1d20 to succeed in these tasks. The proficiency throw required reduces by 1 per level. At first level, a sage may also attempt to read languages on a proficiency throw of 5+ (1 custom power).

At 2nd level a sage gains a bonus language (1 custom power @ 2nd). They continue learn a bonus language at each even level.

At 6th level a sage gains the ability to cast arcane spells. At 8th level they gain the ability to research spells, create potions, and scribe scrolls as a mage of their effective level.

At 3rd, 5th, and 7th level a sage gains a bonus class proficiency.

When a sage attains 9th level (Learned Professor), he can establish a college, and 2d6 0 level students and 1d6 sage apprentices of 1st to 3rd level will come to study. While studying the sage must cover their expenses and they must be paid standard rates for hirelings.

So for the Expert Knowledge proficiency, for two class powers, you've ruled that the Sage counts as having one additional rank in any general proficiency with which he has at least one rank. That seems reasonable to me.